The performance of cellulase mixtures in biomass conversion processes depends on many enzyme properties including stability, product inhibition, synergy among different cellulase components, productive binding versus nonproductive adsorption and pH dependence, in addition to the cellulose substrate physical state and composition. Given the multivariate nature of cellulose hydrolysis, it is desirable to have diverse cellulases to choose from in order to optimize enzyme formulations for different applications and feedstocks.